We propose to apply image-guided parallel robotic technology to create a robot to assist surgeons with acoustic neuroma surgery, improving both the safety and efficacy of demanding acoustic neuroma removal procedures, which require extraordinary precision. This surgical procedure can benefit from the use of a robotic tool because (1) the accuracy of the drill trajectory is of paramount importance for both safety and efficacy, (vital structures lie in close proximity to the bone that must be removed) and (2) it involves rigid anatomy with vital structures encased in bone which does not deform during surgical intervention. Our hypothesis is more rapid, safer, and more accurate access to vital inner-ear structures can be achieved by combining image-guided surgical techniques and miniature parallel robots directly attached to the bone. The clinical innovation in our work comes from the fact that acoustic neuroma surgery has never before benefited from robotic assistance and current surgical robots are not capable of achieving it due to their size and/or lack of abilit to be accurately registered to the patient. Technical innovation comes from the fact that acoustic neuroma surgery requires the smallest, lightest robot that can achieve its challenging accuracy, force, speed, and workspace requirements. Simultaneous optimization of all these factors requires innovation in robot technology, design, and control theory. To achieve this we propose three specific aims. Aim 1 addresses the design our proposed acoustic neuroma surgery robot (ANSR). We will determine design parameters for optimal performance in terms of biomechanical forces, torques, and speeds for surgical drill, and then construct the ANSR robot and associated image-guided surgical system. In Aim 2 we will plan the surgical path and control the robotic system while implementing multiple redundant measures to ensure patient safety. We will apply established registration techniques and create new software that generates a patient-specific motion plan which avoids vital structures and minimizes surgery time, thereby reducing risk to patients. To ensure patient safety, we will the will include throttling, tracking occlusion prevention, emergency stops, drill force monitoring, redundant sensing, and nerve monitoring. Lastly, in Aim 3 we will perform experimental validation studies in phantoms, ex vivo animal bones, and human cadavers using the complete robot system. At the conclusion of this R01, we will have mature hardware and software platforms and will have collected sufficient phantom, animal, and cadaver data to move to human studies through the Food and Drug Administration's Investigational Device Exemption process.